To investigate if the effects seen in vitro would be translatable to an in vivo system, we tested a humanized NSG.Tg(Hu-IL-15) murine model maintaining a mature human NK population and non-humanized NSG murine models receiving either non-transduced or LV/hu-IL-12 transduced A673 (human Ewing sarcoma). The gene discussed is IL15; the disease is Ewing sarcoma.